Created attachment 16687[details]
repro project
### Overview
In the attached repro project, a Canvas with an Ellipse and TextBlock is added the BoxView renderer's Children property. However only the Ellipse is rendered on screen. This worked before Forms 2.0. and both the Ellipse and TextBlock would be displayed.
### Steps to Reproduce
1. Run the attached repro project
### Expected Results
You will see a red circle and text.
### Actual Results
Only the red circle is rendered.
### Version Info
Tested with Forms 2.3 and Forms 2.3.1-pre2

This should be fixed in 2.3.3-pre3. However, please be aware that the fix requires a small change to your WinRT/UWP custom renderers. You will need to add ArrangeNativeChildren = true to OnElementChanged(). Please see https://github.com/xamarin/Xamarin.Forms/pull/322/files for a complete example.
Warm regards,
Xamarin Forms Team